docs(styled-react): update architecture for polymorphic components

[joshblack]

Updates our architecture docs for polymorphic components based on our mob pair today 👀

This helps to address a couple of problems:

• When using the as prop, the base component will not get overriden
• For sx being applied to nested components, this approach should correctly transform sx into className and pass it along
• This will also prevent sx from being passed to the wrapped component

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Pull Request Overview

This PR updates the architecture documentation for polymorphic components in the styled-react package to address issues with the as prop, sx prop handling, and component composition. The changes provide a new implementation pattern that correctly transforms sx into className and prevents sx from being passed to wrapped components.

Key changes:

• Replaces forwardRef pattern with styled-components for polymorphic component implementation
• Adds proper sx prop filtering using shouldForwardProp
• Updates the component creation pattern to use styled-components with sx mixin

[francinelucca]

❤️